Tassilo Parseval <[EMAIL PROTECTED]> writes:
>On Wed, Sep 17, 2003 at 11:39:54AM +1000 Dave Horsfall wrote:
>> Pardon me if this is a FANQ (Freq. Asked Newbie Question), but I cannot
>> find any references to what I want to do.
>>
>> I'm porting some legacy Perl/C code; it was originally done under Perl3
>> (hacked into the function table), thence Perl4 (via userinit() etc). I
>> have the dubious honour of converting it into Perl5/XS.
>>
>> Most Perl/C calls take a variable number of string arguments, and this is
>> where I'm coming unstuck. I've studied both perlxs and perlxstut until
>> I'm practically dreaming XS, but I still cannot find a clear answer.
>>
>> Let's take an example of a user-defined Perl function:
>>
>> $return = &uni_access("record", "key1", "key2");
>>
>
>I don't think you need C_ARGS for that. Your XSUB should begin like
>this (for instance):
>
> int
> uni_access(record, ...)
> char *record; /* const char * may not be in typemap */
> PREINIT:
> char **args;
> register int i;
> CODE:
> New(1, args, items-1, char*);
> for (i = 1; i < items; i++)
> *args++ = SvPV_nolen(ST(i));
> /* now you have "key1" in args[0] and "key2" in args[1] */
> ...
> RETVAL = bla();
> OUTPUT:
> RETVAL
>
>> I implemented the XS stuff as a callable C library, but I have the freedom
>> to change it (and had to, anyway).
If you tell us how the perl4 code worked we may be able to figure
out what to do.
>>
>> So you can see my dilemma; I need to tell the underlying C code how many
>> arguments there are (I cannot change the Perl calls).
>
>Essentially, when working with variadic argument lists, you have the
>special variable 'items' telling you how many arguments were passed. You
>can then use ST(i) (or one of the POP? macros) to access the scalar
Don't use POP macros - use ST(i).
>variables lying on the stack.
>
>You can find more on that in perlxs.pod. See "Variable-length Parameter
>Lists".
>
>Tassilo
